code: def update(self, tree_idx, priority):
      diff = priority - self.tree[tree_idx]
      self.tree[tree_idx] = priority
      while tree_idx != 0:
          tree_idx = (tree_idx - 1) >> 1
          self.tree[tree_idx] += diff
      self._min = min(self._min, priority)
  
file_path: PARL/benchmark/fluid/Prioritized_DQN/proportional_per.py
imports: import numpy
label_desc: Use image node_id 4 for calling the SumTree obj's underlying member method code with example usage: obj.update(tree_idx, priority) without return types